Surface states that have a dz² symmetry around the center of the surface Brillouin zone (BZ) have been regarded common in closely-packed surfaces of rare-earth metals. In this work, we report the electronic structure of dhcp La (0001) thin films by ultrahigh energy resolution angle-resolved photoemission spectroscopy (ARPES) and first principle calculations. Our first principle analysis is based on the many-body approach, therefore, density function theory (DFT) combined with dynamic mean-field theory (DMFT). The experimentally observed Fermi surface topology and band structure close to the Fermi energy qualitatively agree with first principle calculations when using a renormalization factor of between 2 and 3 for the DFT bands. Photon energy dependent ARPES measurements revealed clear kZ dependence for the hole-like band around the BZ center, previously regarded as a surface state. The obtained ARPES results and theoretical calculations suggest that the major bands of dhcp La (0001) near the Fermi level originate from the bulk La 5d orbits as opposed to originating from the surface states.

中文翻译：

---

用光发射光谱法和第一性原理计算研究W（110）上La（0001）薄膜的电子结构

围绕布里渊区（BZ）表面的中心具有dz ²对称性的表面态已被认为在稀土金属的紧密堆积表面中很常见。在这项工作中，我们通过超高能量分辨率角分辨光发射光谱（ARPES）和第一原理计算来报告dhcp La（0001）薄膜的电子结构。我们的第一个原理分析基于多体方法，因此，将密度函数理论（DFT）与动态平均场理论（DMFT）相结合。当对DFT频段使用2到3之间的归一化因子时，实验观察到的费米表面拓扑结构和接近费米能量的能带结构在质量上与第一原理计算吻合。光子能量相关的ARPES测量显示清晰的kZ依赖于BZ中心周围的孔状带，以前被视为表面状态。所获得的ARPES结果和理论计算表明，费米能级附近的dhcp La（0001）的主要谱带起源于整体La 5d轨道，而不是起源于表面态。